You can use untreated pine. I’m not that familiar with the other types of wood and what is safe or not. However you assemble the platform, I’d make sure that the trim pieces could be easily removed and replaced if necessary, esp. in the case of excessive chewing or if they pee on the trim by accident.

Oak is on my toxic list that I refer to alot, so i would definitely not use oak. I don’t see cedar listed anywhere, so I’d just stick to the pine to be safe.

untreated pine is just fine to chew on.

Redwood is another toxic wood to stay away from.

I use the pine for supports in my NIC cube cages, and the bunnies stay away from it for the most part. You might consider building your platform a couple inches longer and wider than your condo, that way the trim would be about an inch away from the cage. I think that if you have trim right up against the cage they are going to be very tempted to nibble on it! Also, I would recommend some kind of water-proof barrier between the bottom of your condo and NIC cage, maybe a layer of linoleum? That way if the bunnies pee on the floor they won’t ruin your platform. You can purchase those linoleum squares that have stickers on the back and just stick them to the top of the platform.

Home Depot sells sheets of rubber type stuff that may provide more traction, I found it in the flooring section, and the rolls are a couple feet wide. I don’t remember it being too expensive but I don’t know what it is called. My bunnies kept eating their carpet and got stasis, so I switched to using seagrass mats, however, these are not wipe-able if they make a mess, so we use a shop-vac to clean them. The bunnies usually eat them within the month anyways so we replace them.

I just bought some ultra cheap thin vinyl and layed it upside down.   The vinyl was really slippery but the back is slightly textured but still washable.  Working ok so far.  Best part is you can by any old vinyl despite colour because you don’t see it anyway.

Rather then carpet, you can use towels or matts and things that are washable -I do that in spots they like to lay down on

Instead of coroplast, I’d also recommend you look into the “peel and stick” linoleum tiles, preferably ones that have a slight texture. I think you can get a box for not too much, plus they are thin enough so you can cut them to fit however you need. And they look nice.

So will this new condo be big enough for 5?